MACKINAW CITY, MI -- Travelers crossing the Mackinac Bridge between Michigan's upper and lower peninsulas Thursday are urged to take extra caution because of high wind speeds in the Straits.

Those with "high profile" vehicles are asked to wait for an escort before crossing, according to a statement posted on the Mackinaw Bridge Authority's website. These vehicles include pick-up trucks with campers; cars with small boats, bicycles or luggage attached to the roof; Ryder of U-Haul trucks; any vehicle pulling a boat; semi-tractors with enclosed trailers and all trailers with side walls over two feet in height.

Motorists are asked to travel at speeds of no more than 20 mph when approaching the bridge. Be prepared to stop.

Bridge authority staff are stationed at both ends of the bridge to provide instructions on how and when to cross.

If conditions change, further steps may be taken to protect motorists as they travel, the bridge authority says.